Fire resistant concrete made with slag from the steel industry

The aim is to design and develop precast fire resistant concrete elements using industrial waste materials.

Concrete was the construction material of the 20th century, and without any doubt, with its improved properties, will be the most used material in the 21st century. Yearly, around 750 million m3 of concrete is produced in Europe, which is equivalent to consumption of around 4 tonnes of concrete per EU citizen. This means that in addition to the 1.5 billion tonnes of cement used worldwide, the concrete industry is consuming 9 billion tonnes of sand and rock and 0.9 billion tonnes of mixing water annually. Any substitution of natural aggregate with industrial by-products is saving natural resources and is ecologically justified. Concrete is a composite material made of aggregate, cement, water and additives, where types and properties of used aggregate play an important role in the final properties of concrete exposed to elevated temperatures, since it occupies about 60 - 80 % of concrete volume. This project is focusing on the improvement of concrete properties when exposed to fire by using slag from the steel industry as the potential fire resistant aggregate. In this research work, heavy emphasis is also given to cement paste behaviour at elevated temperatures. For more than 100 years, a large amount of blast furnace iron and steel slag has been produced as a non-metallic by-product in the steel and iron industry. This non-metallic material developed during metal production can be classified into two main groups: blast furnace slag and steel slag. Some amounts of steel slag still have to be disposed, although the properties and fields of application of slag (mainly for cement and road production) are well known and have been intensively researched. According to an inquiry in 2004 of the European steel industry, approximately 11% of the produced steel slags are still dumped in Europe today, although the percentage can vary from country to country. CROATIA takes around 25 ha of free space in just one factory with an estimated amount of 1.5 million tonnes. One of the possibilities for reducing this waste material is to use it as an aggregate in concrete. During the production process, slags are made at high temperatures (blast furnace slag up to 1,500 degrees Celsius, steel slag up to 1,650 degrees Celsius), and due to this process, organic, semi-volatile and volatile compounds are not present in iron and steel slag. It is assumed that concrete made of this can perform better in fire than concrete made of 'normal' aggregate. The national slag association has recognised blast furnace slag as a type of aggregate that could improve the fire properties of concrete, however steel slags have not yet been researched in that sense. The aim of this project is to research the potential use of slag in concrete prefabricated elements, which are used as fire protection barriers, like walls, doors, suspended ceiling elements, etc. Concrete prefabricated elements will be tested according to actual EU standards for usage in buildings. After this research, if steel slag concrete satisfies the fire testing requirements for buildings, the consortium will consider other applications, such as precast linings for tunnels, warehouses, etc., which should satisfy stricter requirements. The proposed project would also consider new technology for fire resistant precast elements and concrete production with the aim being to keep the costs of construction work at an acceptable level. The project also aims to contribute actively to setting up research activities and results in the civil engineering and industrial community. This project would certainly have a positive impact considering the economical (including increased safety), social and especially ecological aspects (sustainable application for secondary material, reduction of landfill use for waste materials, reducing environmental pollution, etc.).
Project ID: 
4 166
Start date: 
Project Duration: 
Project costs: 
1 000 000.00€
Technological Area: 
Building Materials, Components and Methods
Market Area: 
Manufacture of Building Materials

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